Apparatus for electric cooling



momma v H. F. A; TURRETTRNI APPARATUS FOR ELECTRIC COOLING s SheetsSheet 1 File& Sept. 28, 1926 May 5, 1318 H. F. A. TURRETTINI 1,894,072

APPARATUS FOR ELECTRIC QUQLING Filqd Sept. 28, 1926 3 SheetsShee't 2 May5, 1931.

H. F. A. TURRETTINI APPARATUS FOR ELECTRIC COOLING Filed Sept. 28, 19263 Sheets-Sheet -3 llllllllllllllllllllllllllll I 06 am JZ M PatentedMay-5, 1931 UNITED STATES moron HORACE ERANQOISQADOLPHE TURRETTINI, orGENEVA, SWITZERLAND APPARATUS FOR. ELECTRIC COOLING Application filedSeptember 28, 1926, Serial No. 138,227, and in Germany October 8, 1925.

The object of the present invention is to provide an apparatus for theproduction of cold by the utilization of the phenomenon, known underthe; name Peltier effect,

whereby a cooling in portions of such apparatus is electricallyproduced.

In this method of producing cold by an electric current the coolinsubstance, consisting of a soldered joint etween two conductors ofdifferent compositions, does not undergo any physical or chemicalchange. There is no movement of..material.' There are no movable parts.Moreover, such apparatus can be utilized in any region of temperature,that is to .say, produce a cooling effect no matter what the originalstarting temperature.

Various devices have already been proposed for utilizing the Peltiereffect or phenomenon. The arrangements which are described below providethe means of increasing considerably the refrigerating capacityobtainablefrom a utilization of the effect of this phenomenon. Thefollowing descrip- 5 tion may be readily understood by reference to theaccompanying drawings, in which:

Fig. 1 is a longitudinal section through an embodiment of my invention;7

Fig. 2 is a transverse section of an embodiment of my invention; and

Figs. 3, 4, 5 and 6 are views similar to Fig. 1 of modified embodimentsof my invention.

The cold produced at the joints of the two electrical conductors are bythe Peltier effeet proportional to the intensity of the current. At thesame time, as a result of the phenomenon known as the Joule effect, thecurrent produces, in the complete circuit, an amount of heatproportional to the square 40 of its intensity. Finally the joints whichalternate with the cold joints are heated as the resultof what may bedescribed as an inverse Peltier effect, the resulting heat beinghereinafter called Peltier heat. For utilizing the Peltier cold thecooling couples comprise two distinct regions, that in which the Peltiercold is concentrated and that in which the Joule and Peltier heats aredissipated into the surroundings.

In the cold region it .is necessary to (1) reduce as much as possiblethe Joule heat,

which tends to counteract the Peltier cooling effect; (2) diminish thelosses by thermoconductance through the conductors, which lossesdiminish the amount of the lowering of the temperature at the coldjoint; (3) avoid losses by radiation and convection.

In the hot region it is necessary to facili tate the radiation and theconvection of the Joule and Peltier heats into the surroundingatmosphere and to avoid their transference by thermo-conductance andconvection to the cold region. I

In the region of the cold joints the two metals will have sections ofsubstantially the same proportion as their resistances. This conditionis essential in order to allow the employment of the best currentintensity and diminish in the higliest degree possible the production ofJoule heat and the conductance of heat from the hot to the cold regionwhereby the amount of decrease in the temperature of the latter would bediminished. In the case of certain metals or alloys it is possible toincrease or decrease, up to about 10%, the cross section of that of thetwo metals having the greater resistance, the total cross section of thecouple remaining the same. 'By the use of the aforesaid arrangement itis possible to pass the optimum current through the thermo-couple and toobtain the maximum lowering of temperature at the cold oint.

The cold region of the couples is immersed in a liquid contained in acontainer thermally insulated from the surroundings (as shown in Fig. 1)or in a container housed in a cold chamber thermally insulated from thesurroundings (as shown in'Figs. 4 and 6).

The presence of the liquid around the cold region of the couples and incontact with the said region increases the heat capacity of the saidregion and retains the cold produced which, otherwise, would be lost toa great degree through the outer heat conductivity, 9

i. e. the surrounding liquid serves as a heat insulator.

Figs. 1 and 2 show a couple having its two conductors formed from analloy 2 of bismuth and antimony on the one hand and from antiformtogether a disc in two unequal sectors,

the greater partbeing of bismuth. These two sectors provided with holes4 to increase the heat dissipation, carry terminals 7 and 8respectively. The joint or couple and the ad-.

jacent part olithe conductors dip into a liquid to be cooled containedin a Dewar flask 5. The terminals 7 and 8 are connected respectively tothe positive and negative poles of a direct current generator, and acurrent is established proceeding from the bismuth to the antimonypassing across the joint, which in-being cooled by the Peltier efi'ectlowers the temperature of the liquid. The Dewar flask constitutes thecooling chamber of the system.

The hot region of the couple can be-immersed in a liquid bath the usualconvection currents of which disperse the heat produced by the Jouleeffect and by the Peltier'efl'ect into the surrounding atmosphere. Thisarrangement can be seen in Fig. 3.

With a couple or a multiplicity of couples, all the jointsof which arein the "same plane perpendicular to the direction in which conductorsextend one cannot even with the strongest couples obtain more than acertain lowering of temperature, amounting to 10 or 11, below thesurrounding temperature. This is explained by the losses due to thethermal conductivity across the conductors and by the fact that onecannot exceed a certain current density by reason of the generation ofheat according to the Joule eflect. To obtain a greater cooling at thecold joints it is necessary to increase the length of the cold region ofthe couples and consequently to absorb the Joule heat over a greaterlength. To arrive at this result use is made of staggered auxiliarycouples whose cold joints provide a cooling efiect at the levels wherethey adj oin the portions of longer conductors. In Fig. 3 it will beseen how the first bank of couples 1 and 2, forming a cylinder,.is sur;

rounded by a second bank 9 of shorter couples forming a tube of whichthejdints 1O of the first bank. The conductors of bank 9 are themselvessurrounded by a third bank of couples 11, the joints 12 of which stop ata certain distance from the joints 10 of the second bank, and so on.

There is thus formed a' metallic group whose section increases with theheight in a predetermined proportion so as to absorb the Joule heat atdifferent levels, reducing the losses due to radiation (reduced to theministop at a certain distance from the'joints 6 aeoaova mum by theinsulating medium'surrounding the cold region.) and giving a number ofcooling points capable of attaining a permanent group but also at theinterior in order better to distribute the'cooling points in the wholeof the width of the group.

The insulating 'material 12 separating the couples can be a solidsubstance as shown in Fig. 3. p

In certain apparatus for the purpose of distributing the temperatures,use may be made, in addition to the thermal conductivity, of the naturalconvection currents of liquids as in Fig/1. In other types of apparatusdiaphragms of insulating material 13 can be used as in F ig. 6 toseparate the different liquid levels and prevent convection in thevertical direction; or the variation of density of the liquid withthetemperature may sutfice to maintain around, the region at the lowestlevel the longest couple, thatis at the lowest level, the region ofgreatest density and consequently the most cooled portion of the liquid(Fig. 4). a

For other apparatus with a small number of stages one can use, as inFig. 5, an insulating covering 14 for each stage. The shortest couplesof a particular stage are immersed in a liquid surrounding theinsulating wall of the cold chamber in. which are immersed the couplesof the. lower stage. With this arrangement one can obtain with twostages a lowering of temperature amounting to 17 to 18 below that of thesurrounding temperature. 7

By reversin the direction of current flowing through -%l8 conductors onecan obtain heat at thejoints where with the arrangements previouslydescribed cold is generally produced.

Having now described the invention, what I claim is 1. Apparatus forelectric cooling by the utilization of the phenomenon known as thePeltier effect which comprises a thermocouple constituted of twodifl'erent metallic 2. Apparatus for electric cooling by the utilizationof the phenomenon known as the Peltier effect which comprises athermocouple constituted of a conductor of an alloy of bismuth andantimony and a second conductor of antimony, the cross section of saidtwo conductors being substantially in the ratio as their resistances, anelectrical connection of copper for joining the two parts of thethermo-couple at their cold joint, and a connector secured to the freeend of each of the two conductors whereby'an external source ofelectricity can be connected to said thermo-couple for the production ofa cooling effect.

3. Apparatus for electric cooling by the I utilization of the phenomenonknown as the cured to the free end of each of the two me-' tallic partswhereby an external source 0 electricity can be connected to saidthermo-' couple for the production of a cooling effect.

4. Apparatus for electric cooling by the utilization of the phenomenonknown as the Peltier effect which comprises a thermocouple constitutedof two different metallic parts, the cross sections of said metallicparts being substantially in the same ratio as their resistances, anelectrical connection for join- .ing the two metallic parts at theircold joint, a vessel containing liquid into which said thermo-coupledips, a connector secured to the free end ofeach of the two metallicparts whereby an external source of electricity can be connected 'tosaid thermocouple for the production of a cooling effect,

and means for thermally insulating said vessel and said thermo-couplefrom the surroundings. V 5.Apparatus for electric cooling bythe Iutilization of the phenomenon known as the Peltier effect whichcomprises a multiplicity of closely adjacent thermo-couples consti tutedof different metallic parts and of different lengths which have coldjoints, said cold joints being staggered at different levels so that theshorter thermo-couples have a cooling effect on the,adjacent longerthermo-couples, the cross sections of the metallic parts of each of saidthermo-couples being substantially in the ratioof the resistances of the6. Apparatus for electric cooling by the utilization of the phenomenonknown as the 'Peltier effect which comprises a multiplicity of closelyadjacent thermo-couples constituted of different metallic parts and ofdifferent lengths which have cold joints, said cold joints'beingstaggered at diflerent levels so that the shorter thermo-couples have acooling effect on couples, the cross sections of the metallic parts ofeach of said thermo-couples being substantially in the ratio of theresistances of the parts constituting each thermo-couple, a plurality ofvessels containing a liquid and arranged at different levels foraccommodating the cold joints of said thermo-couples, a receptaclesurrounding all of the aforesaid parts, and connectors secured to thefree ends of said thermo-couples whereby an source of electricity can beconnected to said thermo-couples for-the production of a cooling effect.

7. Apparatus for electric cooling by the utilization of the phenomenonknown as the Peltier effect which comprises a multiplicity ofthermo-couples surrounding each other and constituted of differentmetallic parts having cold joints and free ends, the cold joints of theoutermost thermo-couples being located at higher levels than inner onesand the cross sections of the metallic parts being substantially in theratio of the resistances of the parts constituting each of thecorresponding thermo-couple, a plurality of vessels containing a. liquidand arranged at different levels for accommodating the cold jointsof'said thermo-couples, a receptacle surrounding all of the aforesaidparts, and

connectors securedto the free ends of said thermo-couples whereby anexternal source of electricity can be connected to said thermocouplesfor the production of a cooling or freezing efi'ect.

8. Apparatus as set forth in claim 7 m which diaphragms of insulatingmaterial are interposed between and around the varlous vessels to dividethe space within said receptacle into different stages.

p In testimony whereof I aifix my slgnature.

HORACE FRANCOIS ADOLPHE TURRETTINL parts constituting the thermo-couple,a vessel containing a fluid into which said thermocouple dips, andconnectors secured to the free ends of said thermo-couples whereby anexternal source of electricity can be connected to said thermo-couplesfor theproduction of a cooling effect.

the adjacent longer thermo external

